Iron Panel

Iron deficiency anemia (IDA): Low ferritin (<30), low iron, high TIBC, low transferrin sat (<20%). Anemia of chronic disease (ACD): Normal or elevated ferritin (30-200+), low iron, low TIBC, low transferrin sat. Mixed IDA+ACD: Ferritin 30-100 with low transferrin sat — very common in hospitalized patients. Key point: ferritin is an acute phase reactant. In inflammation, a ferritin <100 may still indicate iron deficiency. Soluble transferrin receptor (sTfR) is elevated in IDA but not ACD.

Iron deficiency without anemia is common and causes symptoms (fatigue, restless legs, hair loss, pica). Screen ferritin in: unexplained fatigue, restless leg syndrome, heart failure (IV iron if ferritin <100 or TSAT <20%), heavy menstrual bleeding, athletes with declining performance, post-bariatric surgery, and celiac disease. Target ferritin >50-100 for symptom resolution in most patients.

Elevated ferritin differential: Most common — inflammation (check CRP), metabolic syndrome/NAFLD, alcohol use, liver disease. Less common — hemochromatosis (check transferrin sat — if >45%, check HFE gene), hemolysis, ineffective erythropoiesis, malignancy (especially hematologic), adult-onset Still disease (very high ferritin >1000 with quotient glycosylated ferritin <20%). Ferritin >10,000: think hemophagocytic lymphohistiocytosis (HLH), adult Still disease, or hepatic necrosis.